Alkyl glycoside its use for cleaning purposes, and cleaning composition

ABSTRACT

The present invention generally relates to an alkyl glycoside of the formula (I): RCH 2  O(G) x  H, wherein R is an alkyl group having a total of 8-12 carbon atoms and containing 2-4 groups of the formula --CH(CH 3 )-- in its carbon chain; G is a monosaccharide residue; and x is 1-4. The invention also relates to the use of the alkyl glycoside as a surfactant in the cleaning of hard surfaces. A composition containing an alkyl glycoside of formula (I), a complexing agent and a solubilizer is also disclosed.

This application is a 371 of PCT/SE94/00198.

This application is a 371 of PCT/SE94/00198.

This invention relates to an alkyl glycoside in which the alkyl group ismethyl-branched, as well as the use of the alkyl glycoside as asurfactant in the cleaning of hard surfaces. The invention also concernsa cleaning composition in which the alkyl glycoside is combined with asolubiliser and preferably also with a complexing agent.

In recent years, attention has focused on alkyl glycosides, since thesehave proved to be more easily biodegradable than other non-ionicsurfactants, such as ethylene oxide adducts of fatty alcohols. U.S. Pat.No. 3,839,318 thus describes the production of alkyl glycosides andalkyl oligosaccharides, such as n-octyl glycoside, n-hexyl glycoside,n-decyl glycoside, n-dodecyl glycoside, isodecyl glycoside, isoundecylglycoside, isotridecyl glucoside and the corresponding oligosaccharides.The United States Stationary Invention Registration H171 states thatalkyl glycosides of formulae R(OG) and R(OG)_(x) are excellentsurfactants. In these formulae, R is an alkyl or alkenyl group which isbranched at the second carbon atom or at a higher carbon atom, thebranch being selected from the group methyl, ethyl, isopropyl, n-propyl,butyl, pentyl, hexyl and mixtures thereof, provided that R contains fromabout 7 to about 30 carbon atoms; G is a saccharide group selected fromthe group glucose, fructose, mannose, galactose, talose, allose,altrose, idose, arabinose, xylose, lyxose, ribose and mixtures thereof;and x is 2 or more. Example 1 contains a description of the productionof two product mixtures substantially made up of 2-ethylhexyl glycosideand isooctyl glycoside, respectively.

DE 20 36 472, EP 306 650, EP 306 651 and EP 306 652, inter alia, alsodescribe alkyl glycosides.

Even though alkyl glycosides generally are easily biodegradable, theyare only used to a limited extent in many ranges of application, such asthe cleaning of hard surfaces, since they are too high-foaming and/orhave too poor a cleaning power. It is therefore a desideratum to providenon-ionic surfactants which are about as easily biodegradable, but whichhave a better cleaning effect on hard surfaces and/or are morelow-foaming than known alkyl glycosides.

According to the present invention, it has now surprisingly been foundthat an alkyl glycosides of formula

RCH₂ O(G)_(x) H (I)

wherein R is an alkyl group having a total of 8-12 carbon atoms andcontaining 2-4 groups of formula --CH(CH₃)-- in its carbon chain, G is amonosaccharide residue, and x is 1-4, is advantageously used as asurfactant in compositions for cleaning hard surfaces. The alkylglycosides of formula I shows good cleaning and wetting properties, aswell as low foaming compared with other alcohols of approximately thesame chain length. In addition, the alkyl glycosides has proved to beeasily degradable and have low biotoxicity. Tests have not shown anyskin irritations caused by the alkyl glycosides. Preferably, there are 2or 3 methyl groups. Compounds in which R contains 9 or 10 carbon atomsand x is 1 or 2 are especially preferred, having a good cleaning powerand being comparatively easy to produce.

The compounds according to the invention can be produced in conventionalmanner by reacting an alcohol of formula

RCH₂ OH (II)

wherein R is as indicated above, with a monosaccharide in the presenceof an acid catalyst, the molar ratio of the alcohol to themonosaccharide being 2:1-80:1. The catalyst may be an inorganic ororganic acid. The reaction is performed under vacuum at 90°-120° C. forabout 1-4 h. Conveniently, the resulting reaction mixture is firstfiltered and then neutralised with an organic and/or an inorganic base,whereupon excess alcohol is carefully removed e.g. by distillation, ifso desired.

The alcohols of formula (I) can be produced in conventional manner bycondensing propene, butene or mixtures thereof, whereupon the di-, tri-or tetramers obtained are prolonged with a carbon atom by theoxoprocess. The resulting aldehydes may then easily be converted to thecorresponding alcohols. The alcohols obtained form a complex mixture ofmethyl-branched structures, although some ethyl substituents may bepresent. The amount of quaternary carbon found in the carbon chain isvery small, and alcohols containing quaternary carbon are to be regardedas impurities not encompassed by the invention. Examples of suitablealcohols are Exxal 9, Exxal 10, Exxal 11, Exxal 12 and Exxal 13, allsold by Exxon Chemical. The monosaccharide used as reactant suitablyconsists of pentose and hexose. Specific examples of monosaccharidesused in the production of the inventive glycosides are glucose, mannose,galactose, talose, allose, altrose, idose, arabinose, xylose, ribose andlyxose. Glucose is usually preferred for commercial reasons.

The alkyl glycosides according to the invention are suitable for use incompositions for cleaning hard surfaces, e.g. for degreasing suchsurfaces or washing up. Excellent results are obtained in the degreasingof lacquered or unlacquered metal surfaces. Apart from the inventivealkyl glycoside, these compositions preferably contain a water-solublesolubiliser and suitably contain a complexing agent.

Examples of solubilisers are alkyl ether polyalkylene glycol, such asmonobutyl diethylene glycol; glycols, such as diethylene glycol,dipropylene glycol and propylene glycol; alcohols, such as ethanol,propanol and isopropanol; alkyl glycosides in which the alkyl group has4-8 carbon atoms; and/or tertiary or quaternary amine alkoxylates inwhich the alkyl group, which may be straight or branched, saturated orunsaturated, has 8-20 carbon atoms and in which 6-30 mol of alkyleneoxide is added per mol of amine. Preferably, 50-100 mol per cent of theadded alkylene oxide consists of ethylene oxide, the remainderpreferably consisting of propylene oxide or a mixture of propylene oxideand butylene oxide. The different alkylene oxides can be added randomlyor in blocks. If the cleaning composition should be exceptionallylow-foaming, the alkylene oxide chain conveniently ends with an additionof 1-5 mol of propylene oxide and/or butylene oxide. The ratio of thesolubiliser to the inventive alkyl glycoside is usually 1:10-5:1,preferably 1:3-3:1.

The complexing agent may be a conventional inorganic or organic agent,such as an inorganic phosphate or NTA, EDTA, citric acid or apolycarboxylate. The amount added may vary from nothing at all to 300%by weight of the inventive alkyl glycoside. Preferably, the quantitativeratio of the complexing agent to the alkyl glycoside is 1:10-2:1.

The cleaning compositions may further contain other additives, such aspH-adjusting agents, antifoaming agents, enzymes, other surfactants andscents. The compositions are usually aqueous and in the form ofemulsions, microemulsions or solutions.

The invention will now be further illustrated by a few Examples.

EXAMPLE 1

An alkyl glycoside was produced by reacting 2.6 mol of an alcohol (Exxal9) of formula (II), wherein R is a C₈ alkyl having a methyl substitutionof about 2 (average value), with 0.4 mol of glucose in the presence of0.015 mol of sulphuric acid as catalyst at 110° C. and 70 mbar. Thereaction was interrupted after 105 min. The resulting product mixturewas treated by distilling off excess alcohol under vacuum. The yield was105 g, consisting of 60% of C₉ -branched alkyl monoglycoside, 15% of C₉-branched alkyl diglycoside and a residue of higher oligomers. Theglycosides had an average degree of polymerisation (DP) of about 1.5.The structure was determined by gas chromatography, mass spectrometryand NMR.

EXAMPLE 2

An alkyl glycoside was produced by reacting 7.6 mol of an alcohol (Exxal10) of formula (II), wherein R is a C₉ alkyl having a methylsubstitution of about 2.2 (average value), with 1.2 mol of glucose inthe presence of 0.015 mol of sulphuric acid as catalyst at 90°-111° C.and 100 mbar. The reaction was interrupted after 120 min. The reactionmixture was treated by distilling off excess alcohol under high vacuum.The yield was 278 g, consisting of 60% of monoglycoside, 12% ofdiglycoside and a residue of higher oligomers. The glycosides had anaverage DP of 1.6.

EXAMPLE 3

Here, 20 ml of each of the cleaning compositions below, diluted with 10parts by weight of water per part by weight of the composition, wasapplied on a vertically arranged iron sheet soiled with mineral oils,soot, salts and clay. After application, the coated surface was rinsedwith water without any mechanical treatment.

    ______________________________________                                                    Composition, % by weight                                          Components    1      2     A    B    C    D   E                               ______________________________________                                        Glucoside (Example 1)                                                                       5                                                               Glucoside (Example 2)                                                                              5                                                        Glucoside A                5                                                  Glucoside B                     5                                             Glucoside C                          5                                        Glucoside D                               5                                   Butyldiethylene glycol     11   11   11   11  11                              Quaternary ethoxy-                                                                          4      4                                                        lated fatty amine                                                             (Berol 555)                                                                   NTA           5      5     3    3    3    3   5                               Water         86     86    81   81   81   81  84                              ______________________________________                                         Glucoside A = 2ethylhexyl-O(G).sub.x H                                        Glucoside B = isooctylO(G).sub.x H                                            Glucoside C = ndodecyl/n-tetradecyl glucoside (APG600, Henkel)                Glucoside D = ndecyl glucoside (Lutensol GD70, BASF) wherein G = glycosid     residue and x = 1.5 (average value).                                     

The attained cleaning effect was assessed with respect to the area ofthe cleaned surface, as well as its actual cleanness, the FIG. 1indicating no improvement and the FIG. 10 indicating a perfectly cleansurface. The following results were obtained.

    ______________________________________                                        Composition  Cleaned surface, cm.sup.2                                                                    Cleanness                                         ______________________________________                                        1            1112           6                                                 2            144            8                                                 A            0              1                                                 B            80             4                                                 C            48             6                                                 D            72             6                                                 E            0              1                                                 ______________________________________                                    

The foaming of the different ready-to-use solutions was measuredaccording to Ross-Miles ASTM D 1173-53. The following results wereobtained.

    ______________________________________                                                    Foam height, mm                                                   Composition   Instantaneously                                                                           After 5 min                                         ______________________________________                                        1             5           0                                                   2             8           0                                                   A             7           0                                                   B             20          3                                                   C             67          63                                                  D             46          45                                                  ______________________________________                                    

It is evident from these results that the alkyl glycosides according tothe invention show an excellent cleaning power and are clearly superiorto alkyl glucosides having a straight carbon chain with 10-14 carbonatoms, while at the same time having an acceptable degree of foaming.The composition containing alkyl glycosides having an alkyl group with 8carbon atoms showed an unsatisfactory cleaning power.

I claim:
 1. An alkyl glycoside of the general formulaRCH₂ O(G)_(x) H(I)wherein R is an alkyl group having a total of 8-12 carbon atoms andcontaining 2-4 groups of formula --CH(CH₃)-- in its carbon chain; G is amonosaccharide residue; and x is 1-4.
 2. The alkyl glycoside of claim 1wherein R is an alkyl group having 9 or 10 carbon atoms.
 3. The alkylglycoside of claim 1 wherein R has a methyl substitution of 2 or
 3. 4.The alkyl glycoside of claim 1 wherein G is a glucose residue.
 5. Thealkyl glycoside of of claim 1 wherein x is 1 or
 2. 6. A method fordegreasing lacquered or unlacquered metal surfaces which comprisesapplying to said surfaces, as a surfactant, the alkyl glycoside ofclaim
 1. 7. A cleaning composition which comprises an alkyl glycoside inaccordance with claim 1, a water-soluble solubiliser and, optionally, anorganic or inorganic complexing agent.
 8. The cleaning composition ofclaim 7, wherein the solubiliser is selected from the group consistingessentially of alkyl ether polyglycols, glycols, alcohols, tertiaryalkylamine alkoxylates, quaternary alkylamine alkoxylates, and mixturesthereof.
 9. The cleaning composition of claim 7 which comprises thesolubiliser in an amount of 1:3-3:1 based on the weight of the alkylglycoside, and a complexing agent in an amount of 1:10-2:1 based on theweight of the alkyl glycoside.
 10. A surfactant for cleaning hardsurfaces which comprises an alkyl glycoside of the general formulaRCH₂O(G)_(x) H (I)wherein R is an alkyl group having a total of 8-12 carbonatoms and containing 2-4 groups of formula --CH(CH₃)-- in its carbonchain; G is a monosaccharide residue; and x is 1-4.
 11. A process forpreparing an alkyl glycoside of formulaRCH₂ O(G)_(x) H (I)wherein R isan alkyl group having a total of 8-12 carbon atoms containing 2-4 groupsof formula --CH(CH₃)-- in its carbon chain, G is a monosaccharideresidue and x is 1-4, which comprises reacting (i) an alcohol of theformula RCH₂ OH (II)wherein R is as indicated above, with (ii) amonosaccharide wherein said reaction is conducted in the presence of anacid catalyst and the ratio of alcohol to monosaccharide is in the rangeof from 2:1 to 80:1.
 12. The process of claim 11 wherein said reactionis conducted at reduced pressure and at a temperature of from 90° C. to120° C.